1. Field of the Invention
The present invention relates to image taking using an ophthalmologic image taking apparatus, and more particularly to a technique suitable for displaying an image in the ophthalmologic image taking apparatus.
2. Related Background Art
It is naturally required for a medical image such as an ophthalmologic image to be accurately recorded as an image. In addition, an equally important requirement in the recording of the medical image such as the ophthalmologic image is to record information on an intended purpose of image taking for an image to be taken, that is, why the image needs to be taken.
The intended purpose of image taking (hereinafter referred to as “image taking purpose”) of the medical image can be recorded by leaving a record of image taking on a patient chart, an image taking instruction sheet, or the like, writing the record into the taken image, or adding data of the record to the taken image in the case of, for example, an electronic image.
Note that it is inefficient to refer to such record in an actual image diagnosis every time the necessity arises. Therefore, it is preferable to conduct the diagnosis while intuitively reading the image taking purpose from the image. Thus, for example, a site of interest is taken so as to be located at the center of a screen, or image taking is conducted with the site magnified. An image reader who views an image taken by such an image taking method can intuitively understand the image taking purpose of the image in a short time, so that image reading and diagnosis can be efficiently performed. Such a method is disclosed in, for example, Japanese Patent Application Laid-Open No. H05-137696, Japanese Patent Application Laid-Open No. H06-165763, or Japanese Patent Application Laid-Open No. H09-173295.
However, according to a photography process using a silver salt material, which has been widely conducted up to now, when a magnified image is to be taken as described above, it is necessary to optically magnify the image and the taken image exists only as the magnified image. Even in a digital photography process which is widely used in recent years, of course, it is possible to conduct the magnified image taking while examining an image taking site at increased magnifications during image taking.
In this example, the image to be examined is viewed in a state in which the image is magnified with the image taking site as the center thereof. Therefore, the image reader can intuitively understand the image taking purpose as described above. However, the image reader cannot view a site other than the region of the image, with the result that it is necessary to find an image including a required site from other images.
On the other hand, because an electronic image is easy to handle, the following operation is possible. That is, an image is taken at a wide view angle, that is, at low power. When detailed examination is required, the image is magnified as needed using, for example, a viewer function of a personal computer by the image reader. Therefore, it is possible to reduce the number of separate image takings with respect to the magnified image and the wide angle image.
In this example, a wide range image can be viewed, so that the degree of freedom of selection with respect to the magnifying power of the image and the magnified site is high. However, to view the magnified image, it is necessary to conduct predetermined operations such as magnifying of the image and selection of a magnifying region, so that image viewing is complicated. In addition, it is extremely hard to understand the image taking purpose of the image, such as the site of interest and the image taking power (that is, the degree of attention to the site) for the image taking, from the image alone.
In an example of an eye fundus image, there are cases where a wide view angle image mainly focused on a posterior fundus including a papilla and a macula is taken in addition to an image of a lesion present in an eye fundus peripheral portion in order to obtain as much information as possible from a single photograph for reducing a burden on a patient. In addition, there are cases where it is difficult to take an image mainly focused on the lesion present in the eye fundus peripheral portion because of poor mydriasis or a defect of the eye to be examined, such as a cataract. When an image in which the lesion portion is shown at some location is just taken, it is hard to intuitively understand an image taking purpose from the single image alone. That is, it is difficult to intuitively understand that the subject of the greatest interest here is the lesion portion present in the peripheral portion although the posterior fundus is shown in the center of the image, or that the lesion portion is present at some position on the image.
When the image taking is conducted while viewing an examination image that has been subjected to an image process such as edge enhancement, contrast enhancement, RGB-corrected display, or band compression and extension according to a subject to be examined, it is possible to more clearly examine a subject image to be taken. Therefore, when such an image is taken and left, this can greatly contribute to intuitively understanding the image taking purpose upon image reading. However, an original image which has not been subjected to the image process cannot be viewed. Thus, a serious problem involves from the viewpoint of a medical image if the original image cannot be viewed and only the intentionally processed image can be viewed.